The present invention relates to a novel process for preparing alkoxytriazolinones, most of which are known and which can be used as intermediates for preparing agrochemically active compounds.
Alkoxytriazolinones and a plurality of methods for their preparation are known and described in the literature.
Thus, for example, the compound 5-methoxy-2,4-dihydro-3H-1,2,4-triazol-3-one (or 3-methoxy-1,2,4-triazol-5(4H)-one) is obtained when the compound ethyl (methoxy-methylsulfanyl-methylene)-carbamidate (or ethyl N-methoxy-(methylthio)methylene!carbamate) is refluxed with hydrazine hydrate in ethanol (cf. J. Chem. Soc. Perkin I 1973, 2644-2646). However, the starting material employed for this purpose is obtained only in unsatisfactory yield, by methylation of methoxythio-carbonylethoxycarbonyl-amine (i.e., ethyl methoxy-(thiocarbonyl)-carbamate or 1-ethyl-3-methyl thioimidodicarboxylate) with dimethyl sulfate.
In the reaction of phenyl cyanate with ethyl carbazate small amounts of the compound 5-ethoxy-2,4-dihydro-3H-1,2,4-triazol-3-one (or 3-ethoxy-.DELTA..sup.3 -1,2,4-triazolin-5-one) are formed (cf. Arch. Pharm. 307 (1974), 889-891). However, the use of this reaction for specifically preparing alkoxytriazolinones has not been disclosed.
A further method for preparing alkoxytriazolinones comprises reacting iminocarbonic diesters with carbazinic esters to give N'-(amino-alkoxy-methylene)-hydrazine-carboxylic esters ("semicarbazide derivatives"), and condensing these intermediates to the corresponding alkoxytriazolinones (cf. U.S. Pat. No. 5,599,945). This preparation route likewise often provides only unsatisfactory yields of alkoxytriazolinones.